commit: 5dbaeaf19b56c5fdda08efd2c994dab8c1e0df81
parent e6185414db8aacf18e4bb150c75356489973abc1
Author: Eduardo Sánchez Muñoz <eduardosm-dev@e64.io>
Date: Thu, 28 Dec 2023 14:04:41 +0100
Create disk images without root
`mke2fs` has a `-d` option that allows to populate the newly created filesystem without needing to temporarily mount it. That allows to use `parted` and `mkfs.ext3` on regular files without needing root access.
Diffstat:
3 files changed, 26 insertions(+), 63 deletions(-)
diff --git a/lib/generator.py b/lib/generator.py
@@ -59,26 +59,16 @@ class Generator():
# argument matrix ... or we could just use ext3 instead which
# is effectively universally the same
if kernel_bootstrap:
- init_path = os.path.join(self.target_dir, 'init')
+ self.target_dir = os.path.join(self.target_dir, 'init')
+ os.mkdir(self.target_dir)
- os.mkdir(init_path)
- self.target_dir = init_path
-
- if self.repo_path or self.external_sources:
- target.add_disk("external", filesystem="ext3")
- target.mount_disk("external", "external")
- else:
+ if not self.repo_path and not self.external_sources:
self.external_dir = os.path.join(self.target_dir, 'external')
elif using_kernel:
self.target_dir = os.path.join(self.target_dir, 'disk')
- target.add_disk("disk",
- filesystem="ext3",
- size=(str(target_size) + "M") if target_size else "16G",
- bootable=True)
- target.mount_disk("disk", "disk")
self.external_dir = os.path.join(self.target_dir, 'external')
- os.makedirs(self.external_dir, exist_ok=True)
+ os.makedirs(self.external_dir)
if self.early_preseed:
# Extract tar containing preseed
@@ -103,10 +93,16 @@ class Generator():
if kernel_bootstrap:
self.create_builder_hex0_disk_image(self.target_dir + '.img', target_size)
- if kernel_bootstrap and (self.external_sources or self.repo_path):
- target.umount_disk('external')
+ if self.repo_path or self.external_sources:
+ mkfs_args = ['-d', os.path.join(target.path, 'external')]
+ target.add_disk("external", filesystem="ext3", mkfs_args=mkfs_args)
elif using_kernel:
- target.umount_disk('disk')
+ mkfs_args = ['-d', os.path.join(target.path, 'disk')]
+ target.add_disk("disk",
+ filesystem="ext3",
+ size=(str(target_size) + "M") if target_size else "16G",
+ bootable=True,
+ mkfs_args=mkfs_args)
def steps(self):
"""Copy in steps."""
diff --git a/lib/target.py b/lib/target.py
@@ -8,10 +8,9 @@ Contains a class that represents a target directory
"""
import enum
-import getpass
import os
-from lib.utils import mount, umount, create_disk, run_as_root
+from lib.utils import mount, create_disk
class TargetType(enum.Enum):
"""Different types of target dirs we can have"""
@@ -24,7 +23,6 @@ class Target:
"""
_disks = {}
- _disk_filesystems = {}
_mountpoints = {}
def __init__(self, path="target"):
@@ -34,15 +32,6 @@ class Target:
if not os.path.exists(self.path):
os.mkdir(self.path)
- def __del__(self):
- for path in self._mountpoints:
- print(f"Unmounting {path}")
- umount(path)
-
- for disk in self._disks.values():
- print(f"Detaching {disk}")
- run_as_root("losetup", "-d", disk)
-
def tmpfs(self, size="8G"):
"""Mount a tmpfs"""
print(f"Mounting tmpfs on {self.path}")
@@ -59,32 +48,13 @@ class Target:
mkfs_args=None):
"""Add a disk"""
disk_path = os.path.join(self.path, f"{name}.img")
- self._disks[name] = create_disk(disk_path,
- tabletype,
- filesystem,
- size,
- bootable,
- mkfs_args)
- self._disk_filesystems[name] = filesystem
- # Allow executing user to access it
- run_as_root("chown", getpass.getuser(), self._disks[name])
-
- def mount_disk(self, name, mountpoint=None):
- """Mount the disk"""
- if mountpoint is None:
- mountpoint = f"{name}_mnt"
- mountpoint = os.path.join(self.path, mountpoint)
- os.mkdir(mountpoint)
- mount(self._disks[name] + "p1", mountpoint, self._disk_filesystems[name])
- # Allow executing user to access it
- run_as_root("chown", getpass.getuser(), mountpoint)
- self._mountpoints[name] = mountpoint
- return mountpoint
-
- def umount_disk(self, name):
- """Unmount a disk"""
- umount(self._mountpoints[name])
- del self._mountpoints[name]
+ create_disk(disk_path,
+ tabletype,
+ filesystem,
+ size,
+ bootable,
+ mkfs_args)
+ self._disks[name] = disk_path
def get_disk(self, name):
"""Get the path to a device of a disk"""
diff --git a/lib/utils.py b/lib/utils.py
@@ -37,16 +37,13 @@ def create_disk(image, disk_type, fs_type, size, bootable=False, mkfs_args=None)
if mkfs_args is None:
mkfs_args = []
run('truncate', '-s', size, image)
- # First find the device we will use, then actually use it
- loop_dev = run_as_root('losetup', '-f', capture_output=True).stdout.decode().strip()
- run_as_root('losetup', '-P', loop_dev, image)
# Create the partition
if disk_type != "none":
- run_as_root('parted', '--script', image, 'mklabel', disk_type, 'mkpart',
- 'primary', fs_type, '1GiB' if bootable else '1MiB', '100%')
- run_as_root('partprobe', loop_dev)
- run_as_root('mkfs.' + fs_type, loop_dev + "p1", *mkfs_args)
- return loop_dev
+ # 1 GiB if bootable, 1 MiB otherwise
+ offset = str(1024 * 1024 * (1024 if bootable else 1))
+ run('parted', '--script', image, 'mklabel', disk_type, 'mkpart',
+ 'primary', fs_type, offset + 'B', '100%')
+ run('mkfs.' + fs_type, image, '-E', 'offset=' + offset, *mkfs_args)
def mount(source, target, fs_type, options='', **kwargs):
"""Mount filesystem"""
